The Birdbear Formation was deposited as the upper part of a widespread marine carbonate and evaporite system prevalent in the Williston basin during the Middle and Late Devonian. Rock facies representing shallow-water and associated carbonate sub-environments are present in the Birdbear. Stillstands of sub-environments and frequency of transitions between sub-environments are similar to those in the underlying Duperow Formation. Evaporites are dominant in the uppermost part of the Birdbear.

Original depositional environments are recognized with subsequent diagenetic events evaluated. The development of interparticle and moldic porosity is outlined, in particular, with reference to dolomite.

Dolomites are prevalent in the upper section of the Birdbear Formation. Evidence suggests shallow intertidal and supratidal conditions with porosity development associated with the dolomites. Overlying limestones and anhydrites act as caprock.

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